The artificial alder and cypress fixed forest has been massively afforested since 1970s and there has been an obvious land use change in Hilly Area of Central Sichuan Basin.Based on the estimation of biomass and NPP of the artificial alder and cypress fixed forest during different growing periods,organic carbon content of every organ of main trees of the fixed forest,yearly organic carbon store and organic carbon density of the artificial alder and cypress fixed forest during different growing periods were respectively analyzed.Then yearly organic carbon store and organic carbon density of the artificial alder and cypress fixed forest were compared to that of agricultural vegetation during the corresponding period.The result showed that during earlier stage the artificial alder and cypress fixed forest yearly stored a small quantity organic carbon.When the age of the artificial alder and cypress fixed forest was nearly 7 or 8 years old,its yearly organic carbon store was equal to that of paddy rice and dry-land.With the age increase of the fixed forest,vegetation organic carbon density of artificial alder and cypress fixed forest increased quickly,and the effect of carbon sink of the forest became more and more obvious.When the age of the artificial alder and cypress fixed forest was bigger than 3 or 4 years old,its organic carbon density was bigger than that of paddy rice and dry-land.When the forest was mature(more than 20 years old),its organic carbon density was more than 5 times of that of the corresponding period of farmland.In order to improve eco-environment and reduce carbon emission,these countermeasures should be taken into account:enhancing protection,prevention and control of plant diseases and elimination of pests of the artificial alder and cypress fixed forest;engaging in saving management of forest and wood;and actively studying and exploring the transform and rational utilization of the artificial alder and cypress fixed forest.